As medical science has progressed, it has become increasingly important to provide non-human interactive formats for teaching patient care. Non-human interactive devices and systems can be used to teach the skills needed to successfully identify and treat various patient conditions without putting actual patients at risk. Such training devices and systems can be used by medical personnel and medical students to learn the techniques required for proper patient care. The training devices and systems can also be used by patients to learn the proper way to perform self-examinations.
As the use of non-human interactive training formats has increased, the need for materials that simulate natural human tissue has also increased. There have been earlier attempts to mimic characteristics of natural human tissues. For example, U.S. Patent Application Publication No. 2008/0076099 discloses human tissue phantoms and associated methods of manufacturing that utilize two-component silicone gels covered by a nylon fabric. Also, U.S. Pat. Nos. 5,805,665, 4,277,367, 5,902,748, and U.S. Pat. No. 6,675,035 each disclose various materials intended to simulate imaging properties of human tissue for various types of imaging techniques. Further, U.S. Pat. No. 6,945,783 discloses a breast examination training system with inflatable nodules that simulate tumors within the breast tissue. While these earlier attempts at mimicking aspects of natural human tissue have been adequate in some respects, they have been inadequate in many respects. Accordingly, there remains a need for materials that better mimic natural human tissue. In that regard, the training of medical personnel and patients is greatly enhanced through the use of realistic hands-on training with devices and systems, such as those of the present disclosure, that better mimic characteristics of natural human tissue than previous materials.
Polysiloxanes are the most common and one of the most important organosilicon polymers used in polymer chemistry. The silanol, SiO(Me)2, is the key functional group in the synthesis of these polymers. It is very important to understand the chemistry of the individual elements of the polymer as well as the behavior of the functional group in order to understand the characteristics of polysiloxane polymers.
Silicon is a Group 4 (IVA) element found in the periodic table beneath carbon, and it is, by far, the most abundant element in the Group 4 elements. Some of its characteristics are similar to carbon, but overall it can be seen as a completely different element. It makes up 27% of the earth's crust by mass, and it is second in abundance in the world (after oxygen). Silicon has semi-metallic properties, thus, it is important in the semiconductor industry with wide ranges of applications in computers and solar energy collection. It is very rare to find silicon by itself in nature; it is usually bound to oxygen as either SiO2 or SiO4. Silicon dioxide has many forms found in nature, the most common being quartz, a major constituent of sandstone and granite, as well as being a major component of glass.
Silicon bonding can be compared to carbon bonding in many ways. Carbon is the backbone of life and can form chains of infinite length. Silane, SiH4, and methane, CH4, are both very stable tetrahedral compounds. As you build chains, however, the carbon chain is stable but the silane chains' stability decreases with length. This is due to many factors: 1) the Si—Si bond is slightly weaker than the C—C bond, 2) the Si—H bond is weaker than the C—H bond, 3) silicon is less electronegative than hydrogen while carbon is more electronegative than hydrogen, and 4) silicon is larger, providing greater surface area, and has low lying d orbitals, which promotes nucleophilic attack.
Polysiloxanes are known for their useful properties, such as flexibility, permeability to gases, low glass transition temperature, Tg, and low surface energy. Polysiloxanes exhibit two types of flexibility: torsion flexibility and bending flexibility. Torsion flexibility is the ability of the atoms to rotate around a chemical bond. Bending flexibility occurs when there is a large hindrance between non-bonded atoms where there are unfavorable torsion angles.
In view of the foregoing, there remains a need for devices, systems, and methods appropriate for use in medical training that include materials that mimic natural human tissue.